There they were, seated side by side at the front of the International House auditorium: Lowell Bergman, renowned for ferreting out information, and Daniel Ellsberg, renowned for leaking it. Yet when Bergman told him WikiLeaks founder Julian Assange had “indicated that you have a copy” of thousands of once-secret, still-classified documents on a thumb drive — “as part of his insurance policy, in case something happens” — Ellsberg just shook his head slowly, lips sealed in a mischievous smile.

Fortunately for those gathered Thursday for a half-day forum on “National Security and Free Speech,” Ellsberg soon proved as outspoken as ever. Nearly 40 years after achieving worldwide fame for releasing the Pentagon Papers, the 80-year-old Ellsberg remains a fervent critic of what he termed the government’s claims of national security “as a kind of synonym for secrecy.”

To Ellsberg, he made clear, the forum’s subtitle — “From WikiLeaks to the Pentagon Papers” — describes a very short line.

In the last of the day’s three panel discussions, Ellsberg traced a moral and ethical thread from his own case to that of U.S. Army intelligence specialist Bradley Manning, alleged to be the source for the leaks of 250,000 diplomatic cables and other secret documents to WikiLeaks last year.

Ellsberg was a military analyst with the RAND Corporation when, in 1971, he gave the New York Times and other news outlets photocopies of a top-secret Pentagon study of U.S. involvement in Vietnam. Publication of the so-called Pentagon Papers — commissioned by his one-time boss, Secretary of Defense Robert McNamara — revealed, among other things, that the administration of President Lyndon Johnson had systematically lied to Congress and the American public about its reasons for escalating the conflict in the mid- to late-1960s.

Ellsberg, who opposed the war, was prosecuted under the Espionage Act, a case that was ultimately dismissed. The Times‘ legal fight to print the documents — following a court-ordered ban on publication — led to a landmark Supreme Court ruling on behalf of freedom of the press.

On Thursday, Ellsberg likened his own motivations to those of Manning, who reportedly has said, “I found I was actively participating in something I was totally against.”

The lies he and his bosses at RAND and the Pentagon had been hiding from the American public, Ellsberg said, “headed us into a disaster, just like the lies that got us into Iraq got us into a disaster.”

Since his arrest last year in Iraq, Manning has been held in the military brig of the U.S Marine base at Quantico, Va., under conditions that have raised widespread concerns of human-rights violations.

The Army private, said Ellsberg, is “already being punished,” despite not having been prosecuted yet. If he did leak the documents, however, “then I take it he came to the same conclusion I did: If you’re actively participating in something you’re totally against, that you feel is wrong, disastrous to the broad sense of the national security of the country… then you should consider doing things that risk your own personal security, your own position, your career, your friends, your freedom and maybe your life.”

Instead of continuing to protect the government in 1971, he said, “I decided to protect the national interest, to follow my oath.”

Bergman, a producer and correspondent for Frontline who teaches investigative reporting at Berkeley’s Graduate School of Journalism — and who was played by Al Pacino in The Insider, a fact-based look at tobacco-industry secrets — observed that Ellsberg was never jailed by the Nixon administration. The Obama administration, by contrast, “has not only incarcerated Manning, but is doing more investigations and prosecutions related to the Espionage Act than any administration in the history of the United States.”

Bergman also cited the government’s failure to keep classified information under wraps, noting that Manning reportedly downloaded thousands of secret documents onto a Lady Gaga CD he brought to work.

“If there is a serious security issue here,” he suggested, “it’s the lack of security that allowed this to happen.”

Ellsberg, however, called the issue “a distraction, because it implies that there’s a major problem here in that the government can’t keep its secrets, doesn’t keep secrets well enough.”

“The problem is not holes in our security system,” he declared, reeling off a series of disasters — from the 9/11 terrorist attacks to the BP oil spill to the Fukushima nuclear crisis — for which he blamed a lack of transparency. “The fact is that government keeps secrets all too well.”

Both men agreed that some secrets should, in fact, remain secret, Ellsberg adding that even Assange’s thinking had “evolved” since his first, indiscriminate document dumps of classified information. (Asked for an example of a government secret that should have been kept, Ellsberg replied, “Two words: Valerie Plame.”)

They were joined on the panel by Robert Cole, an emeritus law professor at Berkeley and a one-time Harvard classmate of Ellsberg. Earlier panels looked at the technical, legal and political issues surrounding security and free speech, and featured a mix of outside experts and campus authorities including faculty members Steven Weber and Dierdre Mulligan, both with the School of Information, and Saira Mohamed, an assistant professor at Berkeley Law.